Conventional storage batteries are generally charged by a commutated AC power supply. To properly charge such batteries, the following constraints should be met: (1) the charging current should be gradually reduced (rather than sharply); (2) a the charging voltage should be maintained at a set differential relative to the storage battery (about 1.35 times); and (3) charging should be prolonged over a longer duration.
In order to gradually reduce the charging current as in (10 above, prior art chargers often gradually raise the charging voltage short of exceeding the 1.35X voltage differential per the second constraint (2) above. The charging time can be minimized by reducing the ripple of the input power supply. The ripple has previously been reduced by incorporating various filters and active devices. Unfortunately, the conventional approach results in a multitude of circuit components and a high production cost.